THE STABILIZING ACTIONS OF ADENOSINE TRIPHOSPHATE AND RELATED NUCLEOTIDES ON CALCIUM-DEFICIENT NERVE

¹ Department of Pharmacology, Cornell University Medical College, New York, New York

The primary aim of this study was to determine whether ATP antagonizes the spontaneous discharge in Ca-deficient nerve. The results clearly showed that ATP and other nucleoside phosphates prevent or abolish the neural effects of Ca deficiency in concentrations which do not affect normal nerve function. Further experiments showed that some free extracellular Ca ions were required for maximal stabilization by these compounds.

A variety of closely related organic phosphates and also inorganic phosphates did not stabilize the Ca-deficient nerve, indicating a high degree of specificity for the nucleoside phosphate structure.

Procaine, atropine, and tubocurarine also stabilized the Ca-deficient nerve, but free extra- cellular Ca ions were not involved in their actions. Thus, the mode of action of these compounds probably differs from that of the nucleoside phosphate.

To account for the stabilizing action of nucleoside phosphate, it is proposed that Ca-nucleoside phosphate complexes form and bind to lipo-protein on the cell surface. In this way, the lipo-protein molecules assume a conformatiomi compatible with the resting state of the membrane.